I've tried a variety of schemes to set the toe-in on an MG TC, and I eventually designed my own gauge. In particular, I wanted a way to measure the toe that gives the same result every time, and that gives the same result when different people use it. This gauge does that. It's also quick and dead easy to use.
Here is what the gauge looks like:
It's made of 1-1/2" square mild steel tube with an 0.065" wall, with two 4" carriage bolts. I'll give the construction details later on.
Here's a detail of one end, seen from above, showing the 5/16-18 carriage bolt that does the actual work (the steel tubing just provides a rigid mount for the bolts):
Here is the gauge in use. The first step is to position the gauge just behind the front tires, adjusting the carriage bolts so the heads press up against the wheel beads.
Then the gauge is moved around to the front of the front tires. On one side, the carriage bolt is pressed up against the wheel. Hopefully, if the wheels are toed in, there will be a small gap on the other side, as shown below (inside the yellow circle). This gap is the "toe." The gap indicates that the front edges of the wheels are closer together than the rear edges, which is "toe in." If the front edges were farther apart than rear edges, that would be "toe-out." For the MG TC, the factory specifies 3/16" of toe-in. I have not found any factory specification for where the toe is to be measured (e. g. at the bead, at the widest bulge of the tire, or at the tread).
Note: if you want to measure the track (front or rear), this gauge would make that pretty easy as well. Just set it up as illustrated, remove it from under the car, and then measure the distance between the carriage bolt heads. You could also check the rear toe, which should be zero unless the rear axle tube somehow got bent.
Here are the dimensions of the gauge: